Sometimes, Broward County seems like the Grand Central Station of the South.

Each year, almost as many people move out as move in -- some to Palm Beach and other counties, others out of state. Only one in six of those newcomers to South Florida stays longer than six years, according to Internal Revenue Service data.

Between 1975 and 1980, a majority of Broward residents packed boxes and moved -- half of them simply to another residence in the county.

Add to that a decade-old population boom and a seasonal influx of 3 million tourists and snowbirds. In Broward, a county in constant motion, the atmosphere can be summed up by one word: transiency.

``The population is constantly growing, but more than that it`s constantly changing,`` says Stuart McIver, a local historian who moved to Broward in 1968. ``People are born here, get their education here and leave, and other people take their place. Everything is always in a state of flux.``

Such mobility understandably leaves many Broward residents feeling unsettled. Sociologists, urban planners and residents themselves describe a sense of rootlessness and a lack of civic pride.

In a recent Fort Lauderdale News and Sun-Sentinel poll, one-third of the respondents said they did not belong to a church or synagogue or any political, civic or neighborhood organization. About one-quarter said they still considered some other place ``home.``

Twenty-three percent said they expect to move away in the near future and that they would look for a place with lower crime risks, better job opportunities and a more relaxed lifestyle.

Kelly Roobin is a 30-year-old property manager who lives in Fort Lauderdale but rents apartments in west Broward. She chose the older city because she felt its neighborhoods had a sense of history.

Her clients in the west are mostly young families and single middle- management employees who came to Broward for jobs. They usually tell her they have trouble making friends here.

``It`s a very tough place to come into,`` she said. ``It can be cold, it can be very fast. Even in a big city, (people) seem to have a sense of belonging. To plop themselves in a South Florida tropical environment leaning toward tourists and having a good time, it`s difficult.

``There`s so many transient people, it`s very difficult to establish roots here.``

Roobin just finished renting 368 units at the Hampton Place apartments in North Lauderdale.

``How can you lease 368 units in 3 1/2 months?`` she wonders. ``Where do those people come from?``

Many of them come from New York, New Jersey, Pennsylvania, Ohio and Illinois, according to migration data. Often, these transplants retain allegiance to their former hometowns and form friendships with fellow Northerners or Midwesterners.

For example, at least three Brooklyn high schools hold annual reunions here. Many large condominiums have New York, Chicago or Philadelphia clubs, and even retired police and telephone workers from New York have their own organizations.

Joe Muller, 44, a former Brooklyn resident, is a member of the Retired Firefighters Association of New York City. He is also president of the West Sunrise Homeowners Association.

``We`ve come down to make a home here,`` said Muller, who runs a beauty shop with his wife and has three children. ``We`re not carpetbaggers to just soak up the sun. I get a little annoyed when I hear people say `my home` and they`re talking about New York.``

Still, Muller had some things to get used to when he moved here in 1979. After the fast pace of New York City life, he grew impatient at the slow but friendly manner of store clerks.

The county`s character has been shaped by its newcomers -- by where they lived and how they adjusted. For example, more than half of Margate`s residents are native Northeasterners, as are 60 percent of those living in Tamarac, according to census data.

By contrast, 40 percent of Fort Lauderdale`s residents are native Floridians or Southerners and only 30 percent were born in the Northeast.

The newly built cities of west Broward also tend to be more ethnically diverse, with many residents of Russian, Polish and Italian descent. Only one of Broward`s 35 Jewish congregations meets in Fort Lauderdale, and it does not yet have a building. West Broward cities house 21 synagogues.

Voting patterns show the older, east-central Broward neighborhoods tend to be more Republican and conservative, while west Broward condominiums are heavily Democratic. Neighborhoods of single-family homes tend to be more mixed in their voting patterns.

Even the Democrats on the east side are more conservative, County Commission Chairman Scott Cowan said, and they tend to support U.S. Rep. E. Clay Shaw and state Sen. Jim Scott, both Fort Lauderdale Republicans.

The differences, Cowan said, are a natural result of retirement and migration patterns.